[gcc/devel/omp/gcc-11] [og10] openacc: Unshare reduction temporaries for GCN

[gcc/devel/omp/gcc-11] [og10] openacc: Unshare reduction temporaries for GCN

[Kwok Yeung]

https://gcc.gnu.org/g:3d7114a04e08fec75d1e1635fbd8f38ed6f7b701

commit 3d7114a04e08fec75d1e1635fbd8f38ed6f7b701
Author: Julian Brown <julian@codesourcery.com>
Date:   Tue Jul 28 06:02:50 2020 -0700

    [og10] openacc: Unshare reduction temporaries for GCN
    
    The GCN backend uses tree nodes like MEM((__lds TYPE *) <constant>)
    for reduction temporaries. Unlike e.g. var decls and SSA names, these
    nodes cannot be shared during gimplification, but are so in some
    circumstances. This is detected when appropriate --enable-checking
    options are used. This patch unshares such nodes when they are reused
    more than once.
    
    2020-07-30  Julian Brown  <julian@codesourcery.com>
    
    gcc/
            * config/gcn/gcn-tree.c (gcn_goacc_get_worker_red_decl): Do not
            cache/share decls for reduction temporaries between invocations.
            (gcn_goacc_reduction_teardown): Unshare VAR on second use.
            * config/gcn/gcn.c (gcn_init_machine_status): Do not initialise
            reduc_decls.
            * config/gcn/gcn.h (machine_function): Remove reduc_decls cache.

Diff:
---
 gcc/ChangeLog.omp         |  9 +++++++++
 gcc/config/gcn/gcn-tree.c | 30 ++++++------------------------
 gcc/config/gcn/gcn.c      |  3 ---
 gcc/config/gcn/gcn.h      |  1 -
 4 files changed, 15 insertions(+), 28 deletions(-)

diff --git a/gcc/ChangeLog.omp b/gcc/ChangeLog.omp
index b1bc945898a..29bcb59eff5 100644
--- a/gcc/ChangeLog.omp
+++ b/gcc/ChangeLog.omp
@@ -1,3 +1,12 @@
+2020-07-30  Julian Brown  <julian@codesourcery.com>
+
+	* config/gcn/gcn-tree.c (gcn_goacc_get_worker_red_decl): Do not
+	cache/share decls for reduction temporaries between invocations.
+	(gcn_goacc_reduction_teardown): Unshare VAR on second use.
+	* config/gcn/gcn.c (gcn_init_machine_status): Do not initialise
+	reduc_decls.
+	* config/gcn/gcn.h (machine_function): Remove reduc_decls cache.
+
 2020-07-30  Julian Brown  <julian@codesourcery.com>
 
 	* config/gcn/gcn-tree.c (gcn_goacc_reduction_teardown): Remove useless
diff --git a/gcc/config/gcn/gcn-tree.c b/gcc/config/gcn/gcn-tree.c
index 58a45e5c5a4..4f339a8864c 100644
--- a/gcc/config/gcn/gcn-tree.c
+++ b/gcc/config/gcn/gcn-tree.c
@@ -310,7 +310,6 @@ static tree
 gcn_goacc_get_worker_red_decl (tree type, unsigned offset)
 {
   machine_function *machfun = cfun->machine;
-  tree existing_decl;
 
   if (TREE_CODE (type) == REFERENCE_TYPE)
     type = TREE_TYPE (type);
@@ -320,29 +319,12 @@ gcn_goacc_get_worker_red_decl (tree type, unsigned offset)
 			    (TYPE_QUALS (type)
 			     | ENCODE_QUAL_ADDR_SPACE (ADDR_SPACE_LDS)));
 
-  if (machfun->reduc_decls
-      && offset < machfun->reduc_decls->length ()
-      && (existing_decl = (*machfun->reduc_decls)[offset]))
-    {
-      gcc_assert (TREE_TYPE (existing_decl) == var_type);
-      return existing_decl;
-    }
-  else
-    {
-      gcc_assert (offset
-		  < (machfun->reduction_limit - machfun->reduction_base));
-      tree ptr_type = build_pointer_type (var_type);
-      tree addr = build_int_cst (ptr_type, machfun->reduction_base + offset);
-
-      tree decl = build_simple_mem_ref (addr);
+  gcc_assert (offset
+	      < (machfun->reduction_limit - machfun->reduction_base));
+  tree ptr_type = build_pointer_type (var_type);
+  tree addr = build_int_cst (ptr_type, machfun->reduction_base + offset);
 
-      vec_safe_grow_cleared (machfun->reduc_decls, offset + 1, true);
-      (*machfun->reduc_decls)[offset] = decl;
-
-      return decl;
-    }
-
-  return NULL_TREE;
+  return build_simple_mem_ref (addr);
 }
 
 /* Expand IFN_GOACC_REDUCTION_SETUP.  */
@@ -497,7 +479,7 @@ gcn_goacc_reduction_teardown (gcall *call)
     }
 
   if (lhs)
-    gimplify_assign (lhs, var, &seq);
+    gimplify_assign (lhs, unshare_expr (var), &seq);
 
   pop_gimplify_context (NULL);
 
diff --git a/gcc/config/gcn/gcn.c b/gcc/config/gcn/gcn.c
index 80f1430cca8..66599afb487 100644
--- a/gcc/config/gcn/gcn.c
+++ b/gcc/config/gcn/gcn.c
@@ -106,9 +106,6 @@ gcn_init_machine_status (void)
 
   f = ggc_cleared_alloc<machine_function> ();
 
-  /* And LDS temporary decls for worker reductions.  */
-  vec_alloc (f->reduc_decls, 0);
-
   if (TARGET_GCN3)
     f->use_flat_addressing = true;
 
diff --git a/gcc/config/gcn/gcn.h b/gcc/config/gcn/gcn.h
index 5ea075fcd7e..cf8fcb4ef74 100644
--- a/gcc/config/gcn/gcn.h
+++ b/gcc/config/gcn/gcn.h
@@ -573,7 +573,6 @@ struct GTY(()) machine_function
 
   unsigned HOST_WIDE_INT reduction_base;
   unsigned HOST_WIDE_INT reduction_limit;
-  vec<tree, va_gc> *reduc_decls;
 
   bool use_flat_addressing;
 };